Fig. 1

Quality arterial stiffness—radiofrequency wall-tracking system. The movement of carotid walls is tracked in the entire region of interest (green rectangle) composed of 32 scanning lines. Continuous orange lines indicate the automatic positioning of wall-tracking points at media-adventitia interface. Continuous green lines display dynamically the amplified vessel wall movement (the real vessel wall movement is “amplified” by a predefined factor). Real-time distension waveforms are displayed at the bottom (blue line). The values of carotid distension (DIST) and minimum diameter (D) are displayed beat-to-beat on the screen, and the mean value (MED) over the last six beats and standard deviation (SD) are continuously calculated. This results in a frame rate of 500 Hz that allows the detection of wall velocity distension up to 36 mm/s. Diameter wall tracking: continuous orange lines without interruptions indicate a good detection